Question: What is the greatest common factor of $12$ and $9$ ? Another way to say this is: $\operatorname{gcf}(12, 9) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $12$ and $9$ The factors of $12$ are $1$ $2$ $3$ $4$ $6$ , and $12$ The factors of $9$ are $1$ $3$ , and $9$ Thus, the greatest common factor of $12$ and $9$ is $3$. $\operatorname{gcf}(12, 9) = 3$